Preparation of pure hydrogen peroxide and anhydrous peroxide solutions from crystalline serine perhydrate

Hydrogen peroxide is one of the most versatile oxidation reagents, still it has not fully been exploited by synthetic chemists since anhydrous (let alone pure) hydrogen peroxide requires hazardous preparation protocols. We have recently reported on the crystallization of serine and other amino acid perhydrates, thus paving the way for a new method for laboratory-scale production of anhydrous hydrogen peroxide solutions. Serine is insoluble in most organic solvents (e.g., methanol, ethyl acetate, and methyl acetate) that readily dissolve hydrogen peroxide. Moreover, since the adduct of hydrogen peroxide and serine is unstable in these organic solvents, crystalline serine perhydrate readily decomposes to give anhydrous solutions of hydrogen peroxide and crystalline precipitate of the amino acid. This procedure can then yield an anhydrous hydrogen peroxide solution in a single step. Moreover, filtration of the amino acid, and room temperature evaporation of the volatile solvent (e.g., methyl acetate), yields over 99% hydrogen peroxide.     

Hydrogen peroxide synthesis by direct photoreduction of 2-ethylanthraquinone in aerated solutions

A new synthesis method of hydrogen peroxide was investigated by the photoreduction of 2-ethylanthraquinone (AQ) in water-insoluble organic solvents. Through optimizing the photoreduction condition including solvent, atmosphere and irradiated time, the photolysis system of 1,3,5-trimethylbenzene/trioctyl phosphate (3:1) solvent mixture under oxygen atmosphere was found to give a high yield of hydrogen peroxide. Furthermore, the formation mechanism of hydrogen peroxide was proposed, i.e. photoreduction and subsequent oxidation of AQ. The photoreduction of 2-ethylanthraquinone undergoes the hydrogen abstraction from solvent to form the anthrahydroquinone, which is subsequently oxidized by oxygen to give hydrogen peroxide.     

Hemoglobin,horseradish peroxidase,and heme-bovine serum albumin as biocatalyst for the oxidation of dibenzothiophene

Hemoglobin, horseradish peroxidase, and bovine serum albumin incubated heme-catalyzed the oxidation of dibenzothiophene into sulfoxide in the presence of hydrogen peroxide. This reaction was carried out in an aqueous buffer containing 25% of water-miscible organic solvents. The observation of this transient state of hemoproteins during sulfoxidation showed heme degradation. None of the compounds usually involved in a classical peroxidative activity mechanism were detected. Furthermore, this activity did not appear to be based on a Fenton-type reaction. The highest degrees of sulfoxidation were obtained with hemoglobin. Under the best conditions of reaction, 100% of dibenzothiophene were converted into dibenzothiophene sulfoxide by hemoglobin. Heat-denatured hemoproteins did keep their sulfoxidation activity. With hemoglobin, a k_cat of 0.22 min^-1 was determined. Nearly the same values were obtained with heat-denatured hemoglobin and bovine serum albumin-adsorbed heme. With horseradish peroxidase, only 4% of conversion was attained. This percentage could be slightly increased by using a less pure peroxidase or heat-denatured peroxidase.     

Kinetics and mechanism of the oxidation of dibenzothiophene in hydrocarbon solution Oxidation by aqueous hydrogen peroxide-acetic acid mixtures

The oxidation of white oil solutions of dibenzothiophene (DBT) by aqueous hydrogen peroxide-acetic acid solutions was studied kinetically at 50–100°. Under these conditions, the rate of DBT oxidation was found to be first order in acetic acid, second order in hydrogen peroxide, and inversely proportional to the water concentration. The activation energy between 50–100° in 64·5% acetic acid was 14 kcal/mole. We have also found that the monoxide is oxidized about 1·4 times faster than DBT. A mechanism consistent with the kinetic data has been postulated. The rate-determining step appears to be attack of a peracetic acid-hydrogen peroxide dimer on the sulfur atom of DBT.     

Regioselective alkene carbon-carbon bond cleavage to aldehydes and chemoselective alcohol oxidation of allylic alcohols with hydrogen peroxide catalyzed by [cis-Ru(II)(dmp)2(H2O)2]2+ (dmp = 2,9-dimethylphenanthroline)

[reaction: see text] [cis-Ru(II)(dmp)2(H2O)2]2+ (dmp = 2,9-dimethylphenanthroline) was found to be a selective oxidation catalyst using hydrogen peroxide as oxidant. Thus, primary alkenes were very efficiently oxidized via direct carbon-carbon bond cleavage to the corresponding aldehydes as an alternative to ozonolysis. Secondary alkenes were much less reactive, leading to regioselective oxidation of substrates such as 4-vinylcyclohexene and 7-methyl-1,6-octadiene at the terminal position. Primary allylic alcohols were chemoselectively oxidized to the corresponding allylic aldehydes, e.g., geraniol to citral.     

Oxidation of dibenzothiophene catalyzed by heme-containing enzymes encapsulated in sol-gel glass

We have encapsulated several hemoproteins in the sol-gel glass to catalyze the oxidation reaction of dibenzothiophene (model for organic sulfur compounds in coal) with hydrogen peroxide. In addition to cytochrome c and myoglobin, which have previously been encapsulated in sol-gel glasses, two other hemoproteins, horseradish peroxidase and bovine blood hemoglobin, have now been successfully immobilized in sol-gel media with the retention of their spectroscopic properties. All four hemoproteins studied also demonstrate similar catalytic activities toward the oxidation of dibenzothiophene as compared with the results obtained with the proteins in solution. In the case of encapsulated cytochrome c, the more water-soluble S-oxide was obtained with much higher selectivity over the less water-soluble sulfone (S-oxide/sulfone = 7.1) as compared to what was obtained in the aqueous/organic medium (S-oxide/sulfone = 2.3). Because of the advantage of easy separation of the encapsulated proteins from the liquid reaction mixture, it is clear from these studies that the immobilization of active hemoproteins in the solid glass media could serve as more practical biocatalysts.     

Selective hydrogen peroxide oxidation of sulfides to sulfoxides or sulfones with MWW-type titanosilicate zeolite catalyst under organic solvent-free conditions

Selective oxidation of sulfides to sulfoxides and sulfones with hydrogen peroxide under organic solvent-free conditions was demonstrated by the MWW-type titanosilicate zeolite catalyst. Sulfides were oxidized smoothly to give sulfoxides with good selectivities at ambient temperature using 1.0–1.2 equiv of hydrogen peroxide with the MWW-type titanosilicate zeolite catalyst. Especially, the Ti-MWW with an interlayer-expanded structure (Ti-IEZ-MWW) catalyst showed high activity with good chemoselectivity for the oxidation of various sulfides. The catalyst is recyclable for at least five cycles, and the only byproduct is water. Sulfides were directly oxidized to give sulfones in high yields by 2.5 equiv of hydrogen peroxide with the MWW-type titanosilicate zeolite catalyst under organic solvent-free conditions.     

On the mechanisms of oxidation of organic sulfides by H2O2 in aqueous solutions

The mechanism of oxidation of organic sulfides in aqueous solutions by hydrogen peroxide was investigated via ab initio calculations. Specifically, two reactions, hydrogen transfer of hydrogen peroxide to form water oxide and the oxidation of dimethyl sulfide (DMS) by hydrogen peroxide to form dimethyl sulfoxide, were studied as models of these processes in general. Solvent effects are included both via including explicitly water molecules and via the polarizable continuum model. The former was found to have a much more significant effect than the latter. When explicit water molecules are included, a mechanism different from those proposed in the literature was found. Specific interactions including hydrogen bonding with 2-3 water molecules can provide enough stabilization for the charge separation of the activation complex. The energy barrier of the oxidation of DMS by hydrogen peroxide was estimated to be 12.7 kcal/mol, within the experimental range of the oxidation of analogous compounds (10-20 kcal/mol). The major reaction coordinates of the reaction are the breaking of the O-O bond of H2O2 and the formation of the S-O bond, the transfer of hydrogen to the distal oxygen of hydrogen peroxide occurring after the system has passed the transition state. Reaction barriers of the hydrogen transfer of H2O2 are an average of 10 kcal/mol or higher than the reaction barriers of the oxidation of DMS. Therefore, a two-step oxidation mechanism in which, first, the transfer of a hydrogen atom occurs to form water oxide and, second, the transfer of oxygen to the substrate occurs is unlikely to be correct. Our proposed oxidation mechanism does not suggest a pH dependence of oxidation rate within a moderate range around neutral pH (i.e., under conditions in which hydronium and hydroxide ions do not participate directly in the reaction), and it agrees with experimental observations over moderate pH values. Also, without including a protonated solvent molecule, it has activation energies that correspond to measured activation energies.     

离子液体耦合有机过氧化物脱除二苯并噻吩的研究

以12-磷钨酸为催化剂,研究了离子液体耦合有机过氧化物脱除二苯并噻吩(DBT)。研究结果表明,单独使用离子[bmim]BF4、[bmim]PF6液体为萃取剂,脱硫率为27.78%~38.76%。以由等体积的H2O2与甲酸制成有机过氧化物为氧化剂,不使用催化剂和离子液体,温度70℃,反应时间6 h,DBT氧化为二苯并噻吩砜的比例为76.6%。在催化剂作用下,将离子液体与氧化剂耦合使用时,脱硫率明显提高。当催化剂与DBT的摩尔比为0.20∶1,氧化剂与DBT的体积比为10∶1,[bmim]PF6离子液体与DBT的体积比为1∶1,在70℃反应6 h后,脱硫率可达98.60%。耦合体系重复使用五次后,氧化脱硫活性没有明显降低。     

Specific features of formyl- and acetylferrocene oxidation with peroxides in water and organic solvents

Specific features of formyl- and acetylferrocene oxidation with peroxides ROOR (R = H, tert-C₄H₉) in different solvents are studied. It is shown that despite of the presence in complexes of strong electronacceptor substituents they can be oxidized with hydrogen peroxide in the absence of strong Brønsted acids. Dilution of water with organic solvent leads to deceleration and complete standstill of the reaction. In the absence of acids the second order of the process with respect to peroxide and first one with respect to the metal complex was evaluated. In the presence of perchloric or trifluoroacetic acid the order with respect to peroxide decreases to the first one. The dependence of the reaction rate on the concentration of acid has an extremum point. The activity of other peroxides in the reaction with the above-mentioned compounds is significantly lower than the activity of hydrogen peroxide. Probable alternative mechanisms of oxidation of the abovementioned ferrocenes with hydrogen peroxide in the presence and in the absence of acids differing in the way of coordination of reagents with one another and considering direct participation of substituent in the oxidation is suggested.     

The application of deuterium-palladium electrodes in the coulometric-potentiometric determination of bases in ketone media

The application of deuterium-palladium electrodes as generator, indicator and reference electrodes for the determination of organic bases in acetone and methyl ethyl ketone has been investigated. Deuterium dissolved in palladium is oxidized at a potential that is close to the oxidation potential of hydrogen in palladium and more negative than the oxidation potentials of the bases titrated, indicator, and the solvents used. The anodic oxidation of deuterium dissolved in palladium proceeds with 100% current efficiency in the solvents investigated. The relative errors for the determination of 5 x 10(-4)M solutions of bases are less than 1%.     

The role of solvent in some oxygen-transfer reactions of peroxy compounds

Solvent–solute interactions in the peroxyacid oxidations are believed to be specific rather than electrostatic in nature. The kinetic solvent effects reported for the oxidations of organic sulfides, olefins, acetylenes, nitrosobenzenes, thioketones, and aryl sulfines reveal that in each case the rates are fast in nonbasic solvents (e.g., benzene, nitrobenzene, and halogenated hydrocarbons) relative to those in basic solvents such as DMF, dioxane, and alcohols. The rates in CF₃CH₂OH and aqueous or partially aqueous media are again higher than those in the basic solvents. This remakably similar pattern of sensitivity of rates to changes in the solvent nature appears to be characteristic of these oxidations as demonstrated by the existence of linear free-energy relationship. The behavior is best understood in terms of cyclic transition states for these oxidations in which charge separation is avoided by intra- or intermolecular hydrogen bonding depending on the nature of the solvent. Solvent effects on sulfoxide oxidation and on oxidations by hydrogen peroxide and t-butylhydroperoxide are also briefly discussed.     

Chemiluminescent reductive acridinium triggering (CRAT)--mechanism and applications

Acridinium esters traditionally are triggered using basic hydrogen peroxide. By serendipity, we have found that acridinium esters can also be triggered with emission of chemiluminescence by reductive triggering, e.g., by zinc metal or reduced forms of ferric and cupric salts. Furthermore, organic reducing compounds like dithiothreitol, tricarboxyethylphosphine or glutathione could be used in combination with organic oxidants like quinones or inorganic ferric or cupric salts. Mechanisms are proposed which involve the intermediacy of superoxide. Two forms of reactive oxygen species (i.e., hydrogen peroxide and superoxide) could be discriminated based on differences in kinetics. Some applications (improved detection of acridinium ester, use of acridinium ester as redox probes) are discussed.     

Magnetically separable polyoxometalate catalyst for the oxidation of dibenzothiophene with H2O2

Two types of polyoxometalate-functionalized magnetic nanoparticles catalysts consisting of H(3)PW(12)O(40) supported on surface-modified Fe(3)O(4) magnetite nanoparticles were prepared using an easy synthetic route and successfully applied for the oxidation of dibenzothiophene. The magnetic catalysts showed a catalytic performance in the oxidation of dibenzothiophene in acetonitrile with hydrogen peroxide, and high conversions were obtained. The catalysts could be easily separated from the reaction solution by applying an external magnetic field and recycled several times.     

清洁催化氧化合成己二酸

以新颖的过氧钨酸盐——有机酸配位络合物为催化剂,在无溶剂和无相转移剂的条件下,用30％的过氧化氢氧化环己烯合成己二酸,其收率可达93－95％。本文讨论了配位体种类及催化剂用量对反应的影响。     

含氧化叔胺侧基的水溶性酚醛树脂的合成与成像性能

本实验通过一锅、两步法制备改性酚醛树脂.首先利用环氧酚醛树脂F-44与二甲胺反应,得到叔胺化酚醛树脂,叔胺化树脂被双氧水氧化后得到最终目标产物,即含强极性氧化叔胺基团的酚醛树脂.实验表明,该新型树脂易溶于水和一些强极性溶剂,如四氢呋喃、乙二醇独甲醚和N,N-二甲基甲酰胺等.在热的作用下,树脂能够分解并失去水溶性,但仍可溶于一些有机溶剂.由该树脂与830 nm激光增感染料匹配使用,树脂体系对红外光敏感,并能够通过中性水显影得到较为清晰的阴图型图像,表明该树脂有望用于免化学处理热敏激光成像领域.     

Ti─Si沸石的催化氧化性能 Ⅰ．烯烃的氧化及骨架钛的作用

详细研究了Ｔｉ─Ｓｉ沸石在Ｈ_２Ｏ_２存在下对氯丙烯的环氧化、苯乙烯的氧化和环己烯的氧化等反应的催化作用．发现上述三种结构的烯烃其主要定向产物并不一致：氯丙烯氧化产物主要为环氧氯丙烷，苯乙烯氧化主要产物为苯乙醛、环己烯氧化主要产物为环己二酮．说明烯烃氧化的主要定向产物的结构依赖于有机底物的结构，并不全都给出环氧产物．在三个反应中，Ｔｉ─Ｓｉ沸石均表现出显著的催化活性，这可能与沸石骨架中钛的存在有关．发现在氯丙烯环氧化反应中，只有ＴＳ－１及ＴＳ－２表现出环氧化活性．推测沸石骨架位中存在的钛在氧化反应中起重要作用．     

Extensive investigations on oxidized amino acid residues in H(2)O(2)-treated Cu,Zn-SOd protein with LC-ESI-Q-TOF-MS, MS/MS for the determination of the copper-binding site

The ESI (electrospray ionization)-Q-TOF (tandem quadrupole/orthogonal-acceleration time-of-flight) mass spectrometer combined with the nano-HPLC (high performance liquid chromatography) system was utilized to pinpoint the Cu-binding site in Cu,Zn-SOD (superoxide dismutase) protein. Cu,Zn-SOD was treated with hydrogen peroxide, intended to specifically oxidize histidine residues coordinated to the copper ion as a mass spectrometric probe. The oxidized Cu,Zn-SOD was then fragmented with the successive treatment of endoproteinase Asp-N and DTT (dithiothreitol). Separation of the peptide mixture with the nano-HPLC and the on-line ESI-Q-TOF MS analysis revealed that only two peptide fragments were oxidized to a significant extent. Further analyses of oxidized peptide fragments with LC-ESI-Q-TOF-MS/MS disclosed that three out of four Cu-coordinated histidine residues were specifically oxidized by action of a redox-active copper ion and hydrogen peroxide, demonstrating the copper-catalyzed oxidation of amino acid ligands could be a versatile tool for the mass spectrometric determination of the copper-binding site. In addition, proline and valine residues in the proximity of the Cu ion were found to be oxidized upon H(2)O(2) treatment.     

血红蛋白在有机溶剂中的电化学行为及其类酶电催化研究

本文研究了Hb/Sol-gel膜修饰碳糊电极在有机溶剂介质中的直接电化学和类过氧化物酶电催化特性。发现在以甲醇、正内醇和乙腈介质中,Hb修饰电极能够实现其与电极之间的直接电子转移,并且电子转移的动力学过程与水溶液体系相似。然而,在这些有机溶剂介质中,电子转移的可逆性不如水介质中好,同时氧化还原峰电位差均不大于水溶液体系,表明有机溶剂对Hb的直接电子转移产生抑制作用。Hb/Sol-gel修饰电极在有机溶剂介质中和水介质中一样,对其特异性底物H2O2产生过氧化物酶的活性,但其活性均不如水溶液体系强。     

Construction and analytical application of a biosensor based on stearic acid-graphite powder modified with sweet potato tissue in organic solvents

A biosensor based on stearic acid-graphite powder modified with sweet potato (Ipomoea batatas (L.) Lam.) tissue as peroxidase source was constructed and applied in organic solvents. Several parameters were studied to evaluate the performance of this biosensor such as stearic acid-graphite powder and tissue composition, type and concentration of supporting electrolyte, organic solvents, water/organic solvent ratio (% v/v) and hydrogen peroxide concentration. After selection of the best conditions, the biosensor was applied for the determination of hydroquinone in cosmetic creams in methanol. At the peroxidase electrode hydroquinone is oxidized in the presence of hydrogen peroxide and the radical formed was reduced back electrochemically at -180 mV vs Ag/AgCl (3.0 mol L(-1) KCl). The reduction current obtained was proportional to the concentration of hydroquinone from 6.2 x 10(-5) to 1.5 x 10(-3) mol L(-1) (r = 0.9990) with a detection limit of 8.5 x 10(-6) mol L(-1). The recovery of hydroquinone from two samples ranged from 98.8 to 104.1% and an RSD lower than 1.0% for a solution containing 7.3 x 10(-4) mol L(-1) hydroquinone and 1.0 x 10(-3) mol L(-1) hydrogen peroxide in 0.10 mol L(-1) tetrabutylammonium bromide methanol-phosphate buffer solution (95:5% v/v) (n = 10) was obtained.